1. Field of the Invention
The present invention relates to an electric shaver and more particularly to an electric shaver that has, on the upper portion of the shaver main body, a cutter head in which a plurality of cutter units that have outer cutters and inner cutters that reciprocate while making sliding contact with the outer cutters are installed side by side.
2. Prior Art
In a typical reciprocating electric shaver, a cutter head is installed on the upper portion of a shaver main body that includes a driving source (motor), a driving mechanism, a power supply, an operating switch, etc. The cutter head is comprised of one or more main cutter units and an auxiliary cutter unit, which are installed side by side. Each of the main cutter units comprises a combination of a foil-form outer cutter and an inner cutter that makes a reciprocating motion while making sliding contact with the inside surface of the outer cutter. The auxiliary cutter unit comprises a combination of a slit-form outer cutter (e.g., an edge-trimming cutter or a rough shaving cutter) and an inner cutter that makes a reciprocating motion while making sliding contact with the inside surface of the outer cutter.
In an electric shaver that has a plurality of cutter units in the cutter head, a single oscillator (oscillating member) is connected to an eccentric pin that is eccentrically disposed on a motor joint portion. A plurality of cutter units are supported on this oscillator, and the inner cutters of the respective cutter units are simultaneously caused to make a reciprocating motion. Such electric shavers are described in U.S. Pat. No. 5,410,811 and Japanese Patent Application Laid-Open (Kokai) No. H9-19574.
In the above-described electric shaver, since the shaver is arranged so that the driving force is transmitted to a plurality of cutter units from a single oscillator and thus causing the respective inner cutters to oscillate, the distance over which the driving force is transmitted from the eccentric pin to the inner cutters of the respective cutter units supported on the oscillator tends to increase. As a result, the oscillation amplitude of the cutter units become larger, and the driving efficiency drops.
Furthermore, since the cutter head is supported on the shaver main body so as to allow free pivoting, the length of the groove formed in the oscillator must be increased if the inclination of the oscillator that is groove-engaged with the eccentric pin is taken into account. Accordingly, the external size of the oscillator must be increased, and this causes the size of the cutter head to increase.